Published by Unseen Progress, an independent publisher of caregiver research. Last reviewed 2026-05-11. Part of the speech and language research overview.
Short answer. The research does not support the common worry that AAC — picture cards, speech-generating devices, or sign — will delay or replace spoken language. Across controlled studies of non-verbal and minimally verbal toddlers, children given AAC alongside speech intervention produce equal or more spoken words than children given speech-only intervention (Romski et al., 2010; Millar, Light, & Schlosser, 2006). Waiting for speech to "come in on its own" before introducing AAC is the position with weaker evidence, not the cautious one.
AAC — augmentative and alternative communication — is an umbrella term covering any communication modality that supplements or replaces spoken language. For a toddler with very limited or no expressive speech, AAC typically means one of three things: a low-tech picture-exchange system (PECS), a high-tech speech-generating device (an app on a tablet that speaks the word when a symbol is pressed), or manual signs.
The American Speech-Language-Hearing Association (ASHA) describes AAC as multimodal communication: the goal is not to pick one channel and stick to it, but to give the child every available route to express a need, request, comment, or refusal while spoken language develops.
The persistent parental and clinician concern is that putting a device in a child's hands removes their motivation to talk. The research on this question is unusually clear.
The mechanism is straightforward. A child who cannot make a request is a child whose communication attempts mostly fail. A child whose communication attempts succeed — by any modality — learns that communication is worth attempting, expands the range of contexts in which they try, and accumulates the kind of joint-attention episodes that drive vocabulary growth.
The research does not support a strict age cutoff, but it does support not waiting. ASHA's position is that there is no minimum age or prerequisite skill for AAC introduction. The Hanen Centre's parent-coaching literature similarly treats AAC as a routine part of early language support for minimally verbal toddlers, not a last resort.
Practical markers that argue for introducing AAC now rather than later:
The decision is not "AAC instead of speech." It is "AAC alongside the speech work we are already doing."
A speech-language pathologist (SLP) running an AAC trial with a toddler typically starts with a small set of high-value symbols — more, help, all done, a favourite food, a favourite activity — and models them during ordinary play and meals. The adult uses the device or sign while speaking the word aloud (this is called aided language stimulation). The child is not required to use the device on demand; the goal is exposure first, then opportunity, then production.
Roberts and Kaiser's meta-analysis of parent-implemented language interventions (Roberts & Kaiser, 2011) found that parent training in responsive communication techniques — including AAC modelling — produced significant gains in child expressive language. Parent involvement is not a nice-to-have in AAC; it is one of the strongest predictors of whether the AAC system will be used outside the therapy room.
A few patterns reliably reduce the benefit of AAC:
If you introduce AAC at 24 months and the child's speech accelerates rapidly, the AAC system fades out of use and no harm is done. If you wait until age four to introduce AAC and the child has spent two years unable to make basic requests, you have lost vocabulary growth, joint-attention opportunities, and — frequently — the child's confidence that communication attempts will work.
ASHA, the CATALISE consensus on developmental language disorder (Bishop et al., 2017), and the Hanen Centre's parent guidance all converge on the same recommendation: a non-verbal toddler should have access to a working communication system now, not after another six months of waiting.
1. Stop treating AAC as a last resort. It is a first-line tool for minimally verbal toddlers, supported by both efficacy data and consensus guidance. 2. Ask the SLP about an AAC trial if your child is 18+ months with fewer than 10 spoken words. You do not need to wait for a formal AAC evaluation to start with a few core symbols. 3. Use the system everywhere — meals, bath, car, playground — not only during sessions. Generalisation is the limiting factor, not skill acquisition. 4. Model with the device while speaking the word aloud. Aided language stimulation is the active ingredient. 5. Track what works for your child, not what looks impressive. A six-symbol board used 50 times a day beats a 200-symbol app used twice.
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